Air Gap Data from CO-OPS

The Center for Operational Oceanographic Products and Services (CO-OPS) of the National Ocean Service (NOS), an organizational element of NOAA, operates and maintains a network of downward-looking long-range microwave sensors for determining the instantaneous clearance or air gap below bridges that span navigable waterways in the U.S. These observations are part of the National Physical Oceanographic Real-Time System (PORTS) Program. The data collected are used to ensure safety of navigation, improve economic efficiency, and protect coastal resources. Included in this data collection are preliminary 6-minute air gap observations from various bridges spanning navigable waterways in the U.S.

The mission of NOAA's National Ocean Service's (NOS) Center for Operational Oceanographic Products and Services (CO-OPS) is to provide the national infrastructure, and the scientific and technical expertise to monitor, assess, and distribute tide, water level, tidal current, meteorological and other coastal oceanographic products and services necessary to support NOAA's mission.

Air gap data are provided through the Physical Oceanographic Real-Time System (PORTS (trademark)) partnership. Under the appropriation specific to PORTS (trademark), CO-OPS manages services for data ingestion, processing, 24-hour real-time monitoring and dissemination of the data.

Air gap data and surrounding tides, currents, and meteorological conditions help vessel pilots safely enter and leave many seaports. This information is critical for pilots to safely navigate a ship under a bridge, especially as U.S. seaports grow and vessels continue to increase in size.

An Air Gap sensor is a downward-looking long-range microwave instrument used for determining the instantaneous clearance (air gap) below various bridges or overpasses that span navigable waterways in the U.S. The data collected are used to ensure safety of navigation, improve economic efficiency, and protect coastal resources. These real-time data are provided at 6-minute intervals. They are released for limited public use as preliminary data, to be used only with appropriate caution when clearing the bridge.

Latest detailed information on sensors and accuracy can be found at: https://tidesandcurrents.noaa.gov/publications/CO-OPS_Measurement_Spec.pdf

The air gap systems have been created by NOAA/NOS to provide the maritime community with improved information of bridge clearances. These real-time data are accurate to within +/- 1 inch. They are released for limited public use as preliminary data, to be used only with appropriate caution when clearing the bridge.

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The air gap systems have been created by NOAA/NOS to provide the maritime community with improved information of bridge clearances. These real-time data are accurate to within +/- 1 inch. They are released for limited public use as preliminary data to be used only with appropriate caution when clearing the bridge.

Observed data are recorded and transmitted; then go through a quality control procedure and are loaded into a database.

The air gap systems have been created by NOAA/NOS to provide the maritime community with improved information of bridge clearances. These real-time data are accurate to within +/- 1 inch. They are released for limited public use as preliminary data, to be used only with appropriate caution when clearing the bridge.

For CO-OPS to adhere to its goal of reliable operation of PORTS and dissemination of quality data, this requires no more than five (5) percent down time or malfunction of any of its systems. This dictates that PORTS be maintained rigorously by personnel with the required expertise.

Raw data have not been subjected to the National Ocean Service's quality control or quality assurance procedures and do not meet the criteria and standards of official National Ocean Service data. They are released for limited public use as preliminary data to be used only with appropriate caution.

Air gap observations are collected at a high frequency and updated for the public every six minutes to account for changes in water level, vehicular loads on the bridge, air temperature, and other factors.